A battery, which has a high application easiness according to a product group, and has an electric characteristic, such as a high energy density, is referred to as a storage battery or a secondary battery, and has been universally applied to an electric vehicle (EV), a hybrid vehicle (HV), and the like driven by an electric driving source, or an energy storage system (ESS), an uninterruptible power supply (UPS) system, or the like driven by an electric driving source, as well as a portable device.
Particularly, in the case of a battery for a vehicle, a plurality of batteries is configured by a serial circuit, and safety, durability, a high output, and the like of the plurality of batteries are influenced by voltage balancing of the battery rack including the battery cells, so that it is necessary to make a voltage of each battery rack be uniform. To this end, there is required voltage balancing between the battery racks so that each battery rack has an appropriate voltage while discharging and charging the battery cells included in the battery racks.
However, the apparatuses and the method for balancing voltages between the battery racks in the related art require a separate power supply device for balancing when a difference in a voltage value between the battery racks is generated, thereby having a problem in a cost aspect.